The present invention relates to a sensitive material or body for electrophotography and a manufacturing method thereof, and specifically to a material and a method of forming a charge-generation layer of a laminated photoconductive layer provided on a conductive substrate.
Conventionally, as materials for forming a photoconductor for electrophotography, inorganic photoconductive materials, such as selenium, selenium alloys, zinc oxides, cadmium sulfides and silicon, and organic photoconductive materials including compounds, such as anthracene, oxadiazole, triazole, imidazolone, imidazole, oxazole, imidazolydine, pyrazoline, benzothiazole, triphenylamine, benzoxazole, polylvinylcarbazole, vinyl polymer, polycyclic quinone, perylene, perynon, anthraquinone, phthalocyanine, dioxazine, indigo, thioindigo, squarylium, azolake, azo, thiapyrylium, quinacridone, cyanin, azulenium, triphenylmethane, hydrazone, triarylamine, triamine, N-phenylcarbazole, stilbene and polysilane, have been used.
A photoconductor has been made by forming a photoconductive layer, which is formed either by sublimation or vapor deposition of the above materials or by the application of a coating liquid containing a solvent into which such materials are dissolved and/or dispersed. A resin binder may sometimes be added to such a solvent as necessary before dissolution or dispersion.
The photoconductor must be able to retain surface charges in dark areas, to receive light to generate charges, and to transport generated charges. The photoconductor therefore includes a single-layer photoconductor constructed of a single material featuring all these functions, a function-separated photoconductor in which such functions are performed by separate materials formed into respective single layers, and a function-separated laminated photoconductor formed of a layer composed primarily of a material capable of generating charges and a layer composed primarily of a material capable of retaining surface charges and transporting charges.
Because of the flexibility, thermal stability, film formation capability, wide variety of materials and spectal sensitivities and low cost, the organic photoconductive materials have received many proposals for the application to the photoconductor, and many attempts have been made for practical use.
For example, anthracene compounds are disclosed in Japanese Patent Unexamined (KOKAI) Publication (herein after referred to JP KOKAI) No. 4-358157; oxadiazole compounds in Japanese Patent Examined (KOKOKU) Publication (herein after referred to JP KOKOKU) No. 34-5466 and U.S. Pat. No. 3,189,447; triazole compounds in JP KOKOKU No. 34-5467; imidazolone compounds in JP KOKOKU No. 34-8567; imidazole compounds in JP KOKOKU No. 34-10366; oxazole compounds in JP KOKOKU No. 35-11218 and JP KOKAI No. 56-123544; imidazolidine compounds in JP KOKOKU No. 35-11217; pyrazoline compounds in JP KOKOKU No. 37-16096, JP KOKOKU No. 52-4188 and JP KOKOKU 59-2023; benzothiazole compounds in JP KOKOKU 35-11219; triphenylamine compounds in U.S. Pat. No. 3,180,730; benzoxazole compounds in JP KOKOKU 35-11219; poly(vinylcarbazole) compounds in JP KOKOKU 34-10966; and vinyl polymer compounds in U.S. Pat. No. 3,162,532.
Phthalocyanine compounds are disclosed in JP KOKOKU 52-1662, JP KOKAI 58-100134, JP KOKAI 58-182639, JP KOKAI 59-44053, JP KOKAI 59-44054, JP KOKAI 59-155851, JP KOKAI 59-215655 and U.S. Pat. No. 3,816,118.
Azo compounds are disclosed in JP KOKOKU 60-45664, JP KOKAI 47-37543, JP KOKAI 56-94358, JP KOKAI 56-116039, JP KOKAI 57-58154, JP KOKAI 57-176055, JP KOKAI 58-122967, JP KOKAI 60-5941, JP KOKAI 60-153050 and JP KOKAI 63-305362.
Triphenylmethane compounds are disclosed in JP KOKOKU 45-555: hydrazone compounds in JP KOKOKU 55-42380, JP KOKAI 54-15028, JP KOKAI 57-101844, and JP KOKAI 1-102469; triarylamine compounds in JP KOKOKU 58-32372; triamine compounds in JP KOKAI 1-219838, JP KOKAI 4-13776, JP KOKAI 4-13777, European Patent No. 455,247 and Denshi Shashin Gakkaishi 29 (4), 366 (1990); N-phenylcarbazole compounds in JP KOKAI 57-148750; and stilbene compounds in JP KOKAI 58-198043.
To form an organic photoconductive material as a photoconductive layer on a conductive substrate, a coating liquid is prepared through the dissolution and/or dispersion of such a material in a solvent. In such a case, as a resin binder, a polycarbonate resin, a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a polyvinyl resin, a silicone resin, an acrylic resin and a copolymer of such resins or corresponding monomers are used individually or in combination as required.
In addition, an organic solvent is often used as a solvent. These organic solvents include aliphatic solvents, such as hexane and cyclohexane; halogenated solvents, such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroathane, 1,1,1-trichloroethane, tetrachloroethylene, trichloroethylene and 1,2,3-trichloropropane; alcohols, such as methanol, ethanol, isopropanol and ethylene glycol; ketones, such as acetone, methyl ethyl ketone, cyclohexanone and isophorone; aromatic solvents, such as benzene, toluene and xylene; ethers, such as dimethyl ether, diethyl ether and tetrahydrofuran; and nitro solvents, such as nitromethane and nitroethane, which are used individually or in combination as required.
When a photoconductor is manufactured, an organic photoconductive material, and if necessary together with a resin binder, is dissolved and/or dispersed in the above organic solvent to prepare a coating liquid, which is then applied to a conductive substrate by a dipping coating method or other method. The solvent is then volatilized by means of reducing pressure, leaving as it is, or ventilating or heating to form a photoconductive layer.
As described above, there is a wide variety of organic materials available for use in many combinations, all of which allow a film to be easily formed by coating and are suitable for the function-separated laminated photoconductor. However, there is no organic material for sufficiently satisfying all the characteristics required for the photoconductor, and the organic material causes an undesirable high residual potential in the photoconductor.
In view of the above problems, an object of the invention is to provide a photoconductor with good electric characteristics, particularly a low residual potential.
Another object of the invention is to provide a method of sensitive body with good electric characteristics easily.